The present invention is directed to a variable power drive employed to drive a sliding side door of a vehicle between its open and closed position.
Power drive systems for opening and closing the sliding doors of vehicles conventionally employ a reversible drive motor coupled to the door through appropriate mechanism to drive the door between its open and closed position. The sliding door is mounted upon the vehicle for forward and rearward movement and is supported for this movement upon tracks which define a horizontal path when the vehicle is parked on level ground. The door is supported upon the tracks by rollers and thus there is very little resistance to movement of the door when the vehicle is level. However, the motor must be capable of supplying sufficient power to drive the door in closing movement if the vehicle is parked facing up hill. This presents a safety problem because a drive motor which has sufficient power to drive the door to a closed position when the vehicle is facing up hill will apply an excess amount of power to the door when the door is closed with the vehicle on level ground. This excess closing force is sufficient to cause injury if, for example, a child's arm is trapped between the closing door and door frame.
The present invention is directed to a variable power drive system for a sliding door which is automatically regulated to apply the minimum amount of closing force necessary when the vehicle is on level ground and to enable the application of an increased closing force sufficient to close the door when the vehicle is parked facing up an incline.